The move comes roughly a month after the studio's "John Carter" became one of the biggest flops in film history, with the company projecting that the adaptation of the Edgar Rice Burroughs novel would lose $200 million.

Ross took over as chairman of the studio in 2009 from Dick Cook after a highly successful run overseeing Disney Channels Worldwide. His mandate was to produce fewer films and focus on movies with heavily branded content that could be seamlessly integrated across the company's sprawling entertainment empire — from its merchandising division to its theme parks.

In particular, his choice of New York advertising outsider MT Carney as marketing chief become a lightning rod for criticism in clubby Hollywood. Instead of shaking things up, rumors swirled that she lacked influence. With the studio actively seeking replacements, Carney stepped down in January.

Ross' tumultuous span at the helm of the studio was in sharp contrast to his work at the company's television arm, where he expanded Disney's share of the tween market with shows like "Hannah Montana" and " Wizards of Waverly Place."

There were hits, to be sure, with "Alice in Wonderland," "Toy Story 3" and "Pirates of the Caribbean: On Stranger Tides" all grossing north of $1 billion. However, those were greenlit under Cook, as was "John Carter."

Ross' short tenure at the studio put him in an awkward position of not getting full credit for the box office smashes, while being blamed for the bombs. The studio's summer slate looks particularly well-stocked, however, with Marvel's "The Avengers" and Pixar's "Brave" coming out in the coming months.

"Prom," a low-budget high-school movie was one of only films wholly developed by Ross to come down the pike, but instead of replicating his winning Disney Channel formula for the big screen, the movie grossed an anemic $10.1 million worldwide.

In a statement Walt Disney Company Chairman Bob Iger praised Ross' work at the company and his role in strengthening the company's kids and family entertainment franchises.

"His vision and leadership opened doors for Disney around the world, making our brand part of daily life for millions of people," Iger said in a statement. "I appreciate his countless contributions throughout his entire career at Disney, and expect he will have tremendous success in whatever he chooses to do next."

Here's the fill text of Ross' note to staff:

For the last 15 years, I have had the opportunity to work with incredibly talented people on behalf of the world's best loved brand. During that time, we've told some amazing stories around the world, created successful TV programming, movies, and franchises that generated new opportunities for the company in the process.

I've always said our success is created and driven by our people – whom I consider to be the absolute best in the business. But, the best people need to be in the right jobs, in roles they are passionate about, doing work that leverages the full range of their abilities. It's one of the leadership lessons I've learned during my career, and it's something I've been giving a great deal of thought to as I look at the challenges and opportunities ahead.

I believe in this extraordinary Walt Disney Studios team, and I believe in our strong slate of films and our ability to make and market them better than anyone else. But, I no longer believe the Chairman role is the right professional fit for me. For that reason, I have made the very difficult decision to step down as Chairman of The Walt Disney Studios, effective today.

It has been my honor to work with such incredible teams – at Disney Channels Worldwide and The Walt Disney Studios and the many other Disney businesses I've had the opportunity to collaborate with. I know I leave the Studios in good hands and, even on separate paths, I am confident we are all destined for continued success.

-Rich

Statement from Bob Iger, Chairman and CEO, The Walt Disney Company For more than a decade, Rich Ross's creative instincts, business acumen and personal integrity have driven results in key businesses for Disney, redefining success in kids and family entertainment and launching franchises that generate value across our entire company. His vision and leadership opened doors for Disney around the world, making our brand part of daily life for millions of people. I appreciate his countless contributions throughout his entire career at Disney, and expect he will have tremendous success in whatever he chooses to do next.